Stihl MS500i cylinder and piston

[TINYHULK]

I read somewhere that more modern saws and designed to run at the 50:1 ratio and not be starving for oil while older saws like a 40:1 mix. Any truth in engineering changing these tolerances over time?

 

[Nutball]

Since these 500i fiascos I have became much more strict about these saws and standards of use. I know one guy I really have to get on about running dull saws and he was the one running it the day before it wouldn’t start for me. He gets so in his feelings he will sit there and fight with the saw versus getting up and putting proper work in on sharpening the chain. Any tips on training newbies on sharpening?

Each morning everyone grabs a saw and sharpens it. Maybe a raise incentive for achieving good and increasingly better sharpening skills. Maybe limit the dull chain runners to only using some undesirable cheap saw until they learn better.

 

[Nutball]

I read somewhere that more modern saws and designed to run at the 50:1 ratio and not be starving for oil while older saws like a 40:1 mix. Any truth in engineering changing these tolerances over time?

The oil changed, I know that. And the EPA changed.

 

[huskihl]

I read somewhere that more modern saws and designed to run at the 50:1 ratio and not be starving for oil while older saws like a 40:1 mix. Any truth in engineering changing these tolerances over time?

Depends on how many hours you’d like to get out of a saw. If you’re happy with 500 hours, then so be it. The emissions system is designed to be compliant for around 300 hours.

I’ve seen saws with bad crankcase bearings at 500 hours on cheap oil. I’ve also seen the same saws go 1500 hours on good oil at a heavier ratio.

Harry homeowner swears by 50:1 because his 028 still runs after cutting his firewood for 30 years. But at 10 hours per year, that’s only 300 hours. Loggers and tree guys might put that many hours on a saw in 3 months.

 

[Wonkydonkey]

so just wondering if the dull chain man has been using it and it gets hotter & hotter then hits something and carries on trying to finish the cut and with the fuel oil mix it lean seizes on the exhaust side along with some carbon.
i know the electronic gubbins should stop it over reving.
Then either he or someone else starts it and then the saw gets some fresh mix and the rear of the piston gets scored due to the front rubbing and pushing the piston back a bit.

If the spark plug coated is with aluminium, it could provide the info that it has been ran a bit since.


Btw.This thread just gets gooder & gooder ..

 

[Moparmyway]

So from what I’ve read, Dominator oil is only recommended in high performance racing engines that produce high amounts of heat. The additives won’t fully burn and actually will leave carbon deposits.
Interceptor oil is recommended… at least if your into spending $20 a pint on oil mix.

I run it in everything, rototiller, hedgetrimmer, weedwhipper, saws, blower, etc …….

Just like said earlier, very very little carbon anywhere on anything run with Dominator. The smaller motors have some oil spooge outta the exhaust, but it just wipes off with a rag.

 

[Moparmyway]

If the spark plug coated is with aluminium, it could provide the info that it has been ran a bit since.


Btw.This thread just gets gooder & gooder ..

 

[Moparmyway]

Depends on how many hours you’d like to get out of a saw. If you’re happy with 500 hours, then so be it. The emissions system is designed to be compliant for around 300 hours.

I’ve seen saws with bad crankcase bearings at 500 hours on cheap oil. I’ve also seen the same saws go 1500 hours on good oil at a heavier ratio.

Harry homeowner swears by 50:1 because his 028 still runs after cutting his firewood for 30 years. But at 10 hours per year, that’s only 300 hours. Loggers and tree guys might put that many hours on a saw in 3 months.

X2 !!

 

[Moparmyway]

Notice which side has the scoring .....


Still only scored on the one side

Here is why I'm still suggesting that the carbon is what started this thing going downhill. I'm not seeing what normally looks like overheating on the piston. The carbon is not sticking to the crown in the exact same pattern as the scoring of the piston & rings. Normally I see overheated pistons in chainsaws have scoring on the PTO side, not just the flywheel side of the exhaust port.


I have the luxury of having this saw on my bench right now, and I havent seen everything failure related in this world, but I have seen alot. I'm allways open to learn more, so I welcome constructive criticism and other viewpoints. I'd like to see what others think, using these pictures (and others that they havefrom other saw pistons/cylinders). I've seen good oils protect saws with dull chains and even less sharp operators. This could very well be the case here, but I really would like to see pictures of those proven failures. Maybe this oil just doesnt protect like we want it to, maybe it does, but its byproduct of doing so kills motors just as good as if it didnt protect metal to metal.

I believe @huskihl hit the nail on the head, better oil protects better and doesnt have carbon flying around damaging rings, pistons, and cylinders.

 

[Moparmyway]

I think these pictures tell a story, keep in mind that I'm taking in everything as a whole, the sum of the parts shown.

Please discuss and mark up the pictures to go along with your suggestions

 

[Maintenance Chief]

Since these 500i fiascos I have became much more strict about these saws and standards of use. I know one guy I really have to get on about running dull saws and he was the one running it the day before it wouldn’t start for me. He gets so in his feelings he will sit there and fight with the saw versus getting up and putting proper work in on sharpening the chain. Any tips on training newbies on sharpening?

I'm not a disciplinary type teaher when it comes to sharpening.
I buy all kinds of sharpening guides and kits then ask the students to try them out to see which ones they prefer. After some inspection and technique instruction I let them keep the guide or kit they like.
Ownership and pride in a small job like sharpening success go a long way .
It's funny but you'd think giving someone a 1000.00 $ peice of equipment would show them to be mindful? But tell them that they can keep a 25$ file guide and its theirs forever usually illicits the desired effect! Also it eliminates excuses, when you inspect the saws at the end of the day there's no good reason to find a beat chain.
In a group of workers you'll find that usually 1 or 2 people will become the standard of a sharp chain , be sure to comment on your appreciation for a good sharpening.
I've had decent success with attracting more flies with honey than sh¡t.
Alls your doing is creating a niche (sharpening) for somebody to rise up in status and have some pride. Unfortunately in any group its a very small ratio of people who are a benefit of production compared to a warm body.

 

[Maintenance Chief]

View attachment 350245 View attachment 350243 View attachment 350239 View attachment 350242 View attachment 350244

I think these pictures tell a story, keep in mind that I'm taking in everything as a whole, the sum of the parts shown.

Please discuss and mark up the pictures to go along with your suggestions

Agreed, on the whole of Maintenance, oil mix and mechanical .
My ProMac800 had the same looking piston, one sided scoring, it was a split in the fuel line. Basically leaned out the saw. I bought it this way because the saw on whole was in beautiful condition.
Having a lean saw with a self feeding chain is a different story though, it would have really been boggy , dull chain it would have been flying in the rpms. I know the fuel injection chainsaw is different but maintenance on a whole plays a part in catastrophic damage.
One thing I find buying chainsaws from the scrapyard is that they all have dull chains.

 

[Moparmyway]

My ProMac800 had the same looking piston, one sided scoring, it was a split in the fuel line. Basically leaned out the saw.

Would you happen to have any pictures of it, and was it scored on the flywheel side of the exhaust port ?

 

[TINYHULK]

View attachment 350245 View attachment 350243

 

[TINYHULK]

Could just be the photo but is the bluing on the clutch normal or is that further sign the saw was ran too hard while dull?

 

[Moparmyway]

Dull chains dont slip the clutch.
Clutch slipping causes it to heat up, and slipping is usually from trying to get a stuck chain going in the cut.
The clutch drum had alot of oily crud built up on it, but the drum really didnt overheat at all, leading me to believe that this saw was used pretty good, with a little slipping here and there, which is normal for a saw in commercial use.

Me, I'm guilty of smoking my clutches every now and then, and yours looks no worse than mine do, certainly nothing in the clutch area needs replacing !!!

 

[Moparmyway]

The main reason why I posted the clutch and drum pictures is to show that whilst there WAS some excess heat on the PTO side from the clutch, it did NOT affect that side of the piston, rings, or cylinder

I believe Stihl did a great job of having the 500i tune itself to any conditions its put into, and the difference between oils is something I've seen in carb'd saws as well.

I have seen every 500i that was ran on good oil serve their owners through dull chains, dull operators, stumping duties, ham fisted dog fans, etc .............. The saw passed a vac test to begin with, and I'll vac test it again after she is fully assembled.

 

[woodfarmer]

Tinyhulk, which oil were you using In the saw?

 

[TINYHULK]

Tinyhulk, which oil were you using I the saw?

Stihl orange for most of its life. The month before it failed was running stihl grey bottles. All at 50:1

 

[TINYHULK]

What’s your method of vac testing the 500i’s? My stihl dealer gave me the pressure tester adapter that has multiple holes and the plug off for the impulse hose. As well as the husqvarna spark plug port tester.